In the building of culverts which pass under the roadway and which are particularly used for the drainage of waters from one side of the roadway to the other, it has been common to use corrugated steel tubing as the conduit means for the culvert and then to build a backfill structure either with rock, gravel or in some cases the actual pouring in situ of concrete side walls or wings and then backfilling between the side walls with appropriate aggregate and then asphalt or other appropriate roadway covering media such as gravel, asphalt, concrete or the like.